1. Field of the Invention
The present invention relates to a metal dome switch, more specifically, to an improved metal dome switch.
2. Description of the Related Art
Taiwanese Utility Model Patent Application Publication No. 420,370 discloses a conventional metal dome switch. As shown in FIG. 1, the conventional metal dome switch 7 comprises a metal spring plate 71, a domed portion 711 formed at the center of the metal spring plate 71, a plurality of wings 712 evenly spaced around the metal spring plate 71, a plurality of winglets 713 each respectively extending from the corresponding wing 712, and a sticker 72 arranged above the metal spring plate 71. The spring plate 71 is mounted on a circuit board 8. A plurality of bumps 81, 82 for connecting a positive electrode and a negative electrode are evenly formed on the circuit board 8. The bump 82 for connecting a negative electrode corresponds to the inner surface of the domed portion 711 of the metal spring plate 71. A membrane 9 provided with a roof portion 91 is arranged above the sticker 72. The roof portion 91 corresponds to the metal spring plate 71 and the membrane 9 is mounted on the circuit board 8, allowing the sticker 72 to be attached between the metal spring plate 71 and the roof portion 91.
Once the roof portion 91 is pressed down, it abuts against the domed portion 711 of the metal spring plate 71, allowing the domed portion 711 to be in contact with the bump 82 of the circuit board 8. The positive electrode of the circuit board 8 is electrically connected with the winglet 713 via the bump 81, allowing the positive electrode to be electrically connected with the negative electrode via the downwardly pressed metal spring plate 71.
However, when the conventional switch 7 is pressed down, the bumps 81, 82 for connecting the positive electrode and the negative electrode are required for the circuit board 8 to be electrically connected with the metal spring plate 71. Such an arrangement needs more parts and causes a higher cost. Moreover, the wing 712 which lacks proper flexibility deforms under the stress from the domed portion 711 and will probably be damaged or even fractured after being used for a long time. Besides, a positioning jig is required when the sticker 72 is manually attached to the metal spring plate 71, increasing the manufacture cost.
Therefore, in view of the above drawbacks of the prior switch, the inventor proposes the present invention to overcome the above problems based on his deliberate researches and related principles.